MVP.css - Minimalist stylesheet for HTML elements andybrewer.github.io
tailblocks — Ready-to-use Tailwind CSS blocks mertjf.github.io
Pylon — Declarative layout primitives for CSS & HTML almonk.github.io
Publii - Open-Source CMS for Static Website getpublii.com
Responsive HTML Email Framework emailframe.work
“How to make your HTML responsive by adding a single line of CSS” medium.freecodecamp.org